Bicycle Mechanics - derailluer mount questions

my new to me gt arrette has an old (ugly altus c90 derailures), the jockey wheels feel rough even after taking them apart and greasing them
questions

the front is an e type
can I just use a "clamp on" of the right diameter clamp (or with shims if needed) the seat post is a 26.8 so it would be a smaller size clamp
Would I need to remove the e type clamp?
Can I just cut it off with a dremel?
do I need to remove the BB?
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the rear derailleur looks like it has a long hanger. "or maybe the pivot is not part of the hanger" it does bolt directly to the frame but the only current shimano that looks like this is the tourney
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even the altus's hole look like it is shorter or the bole for the hanger is through the pivot. can the be used instead
or can I not see the pivot an I am only seeing the mount
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Yes, you can use a clamp on derailleur, as long as the pull direction is correct (many work either top or bottom pull). You also want to be sure that if it's road, compact or mtb specific that it matches the cranks.

As far as the RD goes, use any model that you prefer. the long tongue at the top of your Altus is part of the derailleur, the actual hanger is standard.

I assume you mean the clamp diameter should be 28.6 mm, not 26.8. 28.6 mm is 1-1/8" and is a standard steel bicycle tube diameter for older frames.

doh. yes you are right

Yes, you can use a clamp on derailleur, as long as the pull direction is correct (many work either top or bottom pull). You also want to be sure that if it's road, compact or mtb specific that it matches the cranks.

yup I get that. it's a bottom pull triple.

is the actuation the same for road and mtb. how important is it that I match the big chain ring size (will one designe for a 52 work just fine with a 48 it should be able to get low enough.
do I need to worry about high mount vs low mount I don't think so
this will open up my ebay options if I can use sora or 105 as well as the mtb stuff.
is it likely I will need to grind/ cut or remove the old e type. ( griding means I wont need to source a spacer right)
are shims of on the clamp



As far as the RD goes, use any model that you prefer. the long tongue at the top of your Altus is part of the derailleur, the actual hanger is standard.

oh great so just watch out for a long cage with enough take up (for triple) and 2:1 actuation (only some sram)

You have o get rid of the old mount since it'll be in the way. You can either grind it off near the BB, or take the BB apart and remove it entirely. I don't believe you'll need to replace it with a spacer, but you might.

As far as pull ratios, I don't follow Shimano that closely (Campy/old Suntour), but Hillrider or someone else will confirm that either way.

Shimano's road and MTB front derailleurs do not have the same actuation ratios and should be matched with corresponding shifters if you are using indexing. This is particularly necessary with a triple crank. With friction shifters it doesn't matter.

You can use a front derailleur made for a 52T big ring with a 48T ring if you mount it with the proper clearance but a MTB front derailleur intended for a smaller big ring (44 or 42 typically) will have too sharp a curvature to work at all well with a large ring.

Can I just cut it off with a dremel?

Eeew! Buy the BB tool.

Eeew! Buy the BB tool.
actually I do have one, and a crank extractor, but If i need a spacer then I won't havr\e to source it. I can either take it out and cut it to just have the spacer, or jsut cut it.

Pretty sure you won't need a spacer; if you do, you're in a much better position to turn the bracket into a spacer with it removed.

Shimano's road and MTB front derailleurs do not have the same actuation ratios and should be matched with corresponding shifters if you are using indexing. This is particularly necessary with a triple crank. With friction shifters it doesn't matter.


hmm well the shifters in place are no good. broken springs, and chipped pawls so I sourced st-ef65. I they spec the following front drs fd-m390 FD-M360 FD-M311 FD-M190A FD-M190 FD-M191 all mountain bike drs. so I guess I answered that question.


You can use a front derailleur made for a 52T big ring with a 48T ring if you mount it with the proper clearance but a MTB front derailleur intended for a smaller big ring (44 or 42 typically) will have too sharp a curvature to work at all well with a large ring.

So I am also probably limited to a 48. a 52 might work ( i suppose I could grind the cage, but that seems like a lot of work for 4 teeth)

but I am not changing the cranks anytme soon. and the rings are riveted so they stay untill the are worn out.

It's annoying how FDs aren't as modular as RDs like that...

Notice this RD?

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It's annoying how FDs aren't as modular as RDs like that...

Notice this RD?

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I cant tell what it is but it looks pretty big for that casette

Pretty sure you won't need a spacer; if you do, you're in a much better position to turn the bracket into a spacer with it removed.

Point taken.

I cant tell what it is but it looks pretty big for that casette

It's a Deore with a road cage, just to be different ;)